Automatic feed mechanism for power presses and like machines



c. E. TALLls 2,657,046

PRESSES AND LIKE MACHINES 6 Sheets-Sheet l Oct. 27, 1953 AUTOMATIC FEEDMECHANISM FOR POWER Filed Aug. 20, 1951 C. E. TA LLIS FEE Oct. 27, 1953AUTOMATIC D MECHANISM FOR POWER PRESSES AND LIKE.' MACHINES 6Sheets-Sheet 2 Filed Aug. 2o, 1951 CAMLVZJQJZ; fly/MQW N-m A| AI- L c w.n N Q/N NQ wenn 2 m Nm V ...........H- I@ Q Il L. vwr mV I i f3 L, m E.mv S 2 l m /om ////////v7/ Idv Oct. 27, 1953 c. E. TALLls 2,657,046

AUTOMATIC FEED MECHANISM FOR POWER PRESSES AND LIKE MACHINES Filed Aug.20, 1951 6 Sheets-Sheet 3 I 2 I4 '5 lo I4 9 l2 CM2. MA "ry Sdw-f Oct.27, 1953 c. E. TALLxs 2,657,046 AUTOMATIC FEED MECHA SMF' POWER n lPRESSES AND LIK AGHI med Aug. 2o, 1951 e sheets-sheet 4 f le 2 3 IG 5 32a \32 42/ N k /Nv y Oct. 27, 1953 Q E TALL|5 2,657,046

AUTOMATIC FEED MECHANISM FOR POWER PRESSES AND LIKE MACHINES 6SheetsSheet 5 Filed Aug. 20, 1951 FIG. IO.

Flats. CAM/4 N444; 47 M #MJ D MECHANISMFOR POWER PRESSES AND LIKEMACHINES 6 Sheets-Sheet 6 Filed Aug. 20, 1951 Patented Oct. 27, 1953AUTOMATIC FEED MECHANISM FOR POWER PRESSES AND LIKE MACHINES CharlesEdward Tallis, Birmingham,

England,

assignor toBirmingham `Tool & Gauge Company Limited, Handsworth, EnglandApplication August 20, 1951, Serial No. 242,763 In Great Britain August29, 1950 6 Claims. 1

This invention comprises improvements 'in or relating to automatic `feedmechanism for power presses and like machines. The object of the presentinvention is `to provide a hydraulically operated feed mechanism,wherein the pitch of the feed can be readily adjusted whilst the pressor like machine is in operation. A further object of this invention isto provide means whereby the extent of intermittent feed movement of thestrip or like stockbeing fed can be infinitely varied between limits.

Referring to the drawings,

Figure 1 is a plan view of strip feeding means according to thisinvention.

Figure 2 is a sectional elevation taken on the line 2 2 of Figure 1 asregards the upper part of the elevation, the lower part corresponding toa section taken on theline 2 2 of Figule.

Figure 3 is a cross sectional view taken on the line 3 3 of Figure 1 orFigure 2.

Figure 4 is a cross sectional view taken on the line 4 4 of Figure 1.

Figures 5, 6 and '7` are detail cross sectional plan views taken on thelines 5, 6 6 and 'I 'I re-` spectively, of Figure `2.

Figures 8 and 9 aredetail cross sectional views taken on the lines 8 8and 9 9 respectively of Figure 2.

Figure 10 is a cross sectional elevation of the pump or impeller.

Figure 11 is a view taken on the line II II of Figure 10, i. e. an endview of the impeller with the cover removed.

Figure 12 is a viewof the other end of the impeller, and

Figure 13 is a detail sectional view on an enlarged scale of one `of theimpeller plungers showing the automaticreplenishing valve mechanismtherein.

In herein describing the invention with reference to the accompanyingdrawings as applied to means for feeding strip metal, a generaloutlineof same is rstgiven, the various parts being subsequently described indetail.

Referring to Figures 1 and 2 the base II of the machine houses a blockassembly I containing valve controlled ducts on `which is mounted asupport member 2 for two hydraulic rams in the form of two parallelcylinders 3, 4 containing pistons 5, E respectively, arranged to operatein opposite directions (see Figure l) on a suitable table I carried by asaddle 8 which slides, on the cylinders 3, `II so that the latter form`guides for slidably supporting, the table .'I. l

Carried at one end, of the table, 1 a. gripper unit 9, whilst a similarfixed gripper unit I0 ex,- tends across the table and is mounted on thebase II. Both these gripper units have hinged covers I2 `acting as anormally xed pressure pad and arranged to open bookwise in the body partof the gripper unit to enable the strip (indicated by the chain dottedline I3) to be placed on pads I4 within each unit, a rubber diaphragm I5being placed underneath each pad I 4 so that on hydraulic uid such as asuitable oil being fed under the diaphragm I5 the pad I4 is urgedtowards thecover I2 to grip the strip |13 when the cover is secured inthe closed position by the fastening means 56.

The cylinders 3, 4 are connected through the valve block I by means ofpipes I6, I' to an impeller (Figure 10) for forcing and withdrawing oilalternately from said cylinders 3, 4. Thus on oil being forced to theforward cylinder 3 the table is moved forward, oil being expelled fromthe return cylinder 4 and vice versa, the two columns of oil from thecylinders via the block I and pipes IS, Il to the impeller acting afterthe manner of hydraulic push rods, the oil of each column alternatelymoving to and fro.

The oil line connected by the pipe Il passes directly through the blockI to the forward cylinder 3, but the other oil line is led to the returncylinder 4 through the pipe I5 via a series of valve controlled ducts inthe block I whereby the reciprocating motion of the table I iscontrolled in relationto the opening and closing of the gripper units S,IB which are operated by a separate hydraulic system comprising mainlythe operating piston I8 and a small reservoir I9 (see Figure 2).

The arrangement issuch that just prior to the commencement of a forwardmovement of the table the. gripper unit 9' grips the strip I3, Whilstthe unit I0 releases its grip thereon enabling the strip to be fedforward by forward movement of the table "l. Upon the table reaching itsextreme forward position it pauses for an instant suncient for thegripping'unit 9 to release its grip on the strip I3, whilst at the sametime the gripper unit lil grips the strip and holds it while the tableeffects a return movement with the released gripper unit 9, it will thusbe seen that by repeated reciprocatory cycles of the table l the stripis fed forward intermittently for the purposes of having a stamping,pressing or like operation performed thereon by a machine on whichfeeding means according to this invention is installed.

The impeller (Figures 10 to 12) is arranged to have an infinitelyvariable stroke which is adjusted by means of the control knob 25 sothat the extent of travel of the table i per cycle can be adjustedwithin limits to enable a feed of the strip I3 to be readily set inaccordance with requirements and so enable the most economical use ofthe strip to be effected especially in stamping or pressing operations.

For each rotation of the impeller mechanism a complete feeding cycle ofthe table i is effected so that the impeller may be directly driven fromthe machine in order to operate the feeding means in correct timedrelationship with the pressing, stamping or like operations of themachine.

The connection by means of the pipes it, Il between the irnpeller andthe table unit enables feeding means according to this invention to bereadily installed on various types of presses and like machinesrequiring intermittent feed of strip metal or similar stock for whichpurpose the pipes I6, I'I are preferably of copper or like ductile metalso that they may be readily bent in accord- Y ance with the requirementsof a particular installation. l

In cases where the stock to be fed consists of thin strip (i. e. lessthan .013 thick.) two table units are preferably employed one each sideof the press table or the like and operated in unison by a commonimpeller so that one table unit feeds the strip onto the press tabiewhilst the other pulls the scrap strip oif it, thus avoiding stripflexure or buckling which may be further avoided by arranging the tableunit pulling the scrap strip to put a slight tension on the strip.

For supporting very thin strip (of the order of 0,05) against` buckling,the movable gripper unitof each table unit may have a rearward extensionconstantly and slidably engaging a forward extension on the fixedgripper unit.

Describing now in detail with reference to Figures 1 to 9 theconstruction and operation of the table unit and gripper units 9, i3thereon and the oil movement through the block l to the cylinders 3 d itis assumed that the table 'I has just reached its extreme returnposition in readiness to commence a feeding cycle, in which case thefixed gripper unit Ib is still closed and gripping the strip i3, whilstthe movable gripping unit 3 is open.

In order to feed the table forward, oil movement takes place from theimpeller (Figure lo) via the pipe I7, and vertical ducts 2l (Figure 4)and 22 in the block I and cylinder support 2 respectively, to theforward cylinder 3. However, before the piston is moved by the oil to inturn move the table "i, the oil movement first takes place along ahorizontal duct 23 (Figure 6) communicating the vertical duct 2l to oneend of a small piston 24 to move the latter to the right. This causesdisplacement of oil from the bore of the block` I in which the piston 2Aoperates into the horizontal duct 25 Via the short duct 43, oil movementin said duct taking place in the direction towards the vertical duct 25(Figure 2) and from thence to one end of a reduced portion 2i of thepiston I8 causing the latter to move to the left and so actuate theseparate hydraulic system controlling the gripper units.

When oil is displaced into the horizontal duct 25 it can only move inthe direction above mentioned by reason of the fact that movement in theopposite direction i. e. to the left in Figure 6 is checked by the valvemember 3S (Figure 2) until a predetermined oil pressure is reached,since the left hand end of the horizontal duct 25 communicates with thevertical duct 3S (Figure 9) which in turn communicates with the annularspace 3S around the valve member 39 by means of the short horizontalduct 3i. The valve member 39 is provided with a locally reduced part iii(Figure 2) which allows passage of oil into the horizontal duct il whena predetermined oil pressure is reached sumcient to move the valvemember 3S against its spring 5I, the loading of which is set by thescrew means 52.

It will also be noted that the vertical duct 33 (Figure 9) communicateswith a horizontal duct 50 to enter the annular space 49 around the valvemember but thisrvalve cannot be lifted in the manner of the valve member39, and furthermore, a fiat 43 (Figure 2) on this valve member permitspassage of oil to the rear thereof, so that whatever the pressure of theoil supplied to the annular space di] the valve member :i5 is held onits seat by the oil passing to the rear of the valve member by the saidiiat 43.

The movement of the piston I8 to the left expels oil from the bore 53 inwhich it operates via the port 23 (Figure 5) and a flexible pipe 35 tothe movable gripper unit S to cause the latter to grip the strip I3 asoil displacement due to movement of the piston i3 causes the space underthe diaphragm i5 of the said gripper unit 9 to become filled with oil.At the same time the movement of the piston I8 lcauses oil to be drawninto its bore on the other side of said piston from the fixed gripperunit iii via the duct 29 (Figure 3) in the bracket 33 supporting saidgripper unit, the duct the pipe Si and port 32 (Figure 5).

In order to replenish the bore 53 in which the piston i2 (Figures 2 and5) operates to compensate for any oil loss, the reservoir i9communicates with the said bore 53 by means of a small vertical duct 5d(Figure 5) to an annular groove 55 in said bore.

It will, therefore, be seen from Figure 2 that the small piston 24%allows lost motion in the oil movement from the pipe ii to the forwardcylinder 3 to effect by simultaneous operation of the piston i3, achange of the gripping action of the gripper units on the strip i3before the table 'I commences to move forward. The table l then movesforward moving with it the strip I3 gripped by the unit 9, which stripis drawn through the open xed gripper unit it.

As the table i' moves forward oil is expelled from the return cylinder iowing to the return of the piston 3 therein, oil movement taking placedown the vertical ducts 34 and 23 (Figure 4) in the cylinder support 2and block I respectively and horizontal duct 25 (Figure 6) after whichthe oil movement continues up the vertical duct 36 (Figure 9) and viathe horizontal duct 3l and is transferred to the annular space 38 aroundthe spring loaded valve member 39. As already described the valve member39 is provided with a locally reduced part di? (Figure 2) which allowsthe oil above a predetermined pressure to move past the valve into thehorizontal duct di to the vertical duct (i2 which communicates directlywith the pipe I6 to the impeller, the suction to the impeller duringthis phase of the cycle assisting the aforesaid oil movement through theblock I from the return cylinder 4, Again as already dcscribed oilmovement is not permitted from the duct 35 past the valve member 45.

Upon the table reaching its extreme forward movement the impellerreverses the oil movement and commences to force oil along the pipe I6and withdraw same along the pipe I1. The return Ablock I andthefvreturncylinder `4 is yas Lfollows:

The oilmoves `up the vertical duct 42 (Figure 2) where it is in contactwith the other reduced end 44 of the piston I8 and also is in contact`with Athe end of the-spring loaded valve member 45. However, owing to-the load seton this valve member by the settingV of the screw means 46,

`compressing the springr41 urging said valve member, movement ofthelpiston I8rst takes place to displace oil to the fixed gripper unitIllto cause nit to grip the strip I3, whilst ythemovement of the 4pistonI8 simultaneously effects withdrawal `of oil from the moving ngripper`unit 9 to cause same to release the strip I3, the movement `of .thepiston I8 also causing its reduced end 21 to effect oil movement downthe duct 26 to the duct A1'25, where, by means ofthe short duct 48(Figure 6) it acts upon the other end of the small piston 24 to returnsame to the position shown in Figure 6. Here again the lost motionafforded tothe oil movement from the pipe I6 to the return cylinder 4 bythe pistons I8 and 24, enables the gripping action of the gripper `unitsto be changed over, whilst the table 1 is stationary before it startsits return movement.

After the piston I8 has thus effected its movement to change over thegripping action, pressure of the oil between the reduced end 44 and thevalve member 45 is able to overcome the latter, so that oil movementtakes place into the annular space 49 to pass into the horizontal duct56 and clown the vertical duct 36 (Figure 9) to the horizontal duct 2,5which communicates with the return cylinder A4 via the vertical ducts 26and 34 (Figures 2 and 4) to act upon the piston 6 for effecting returnmovement of the table 1.

Whilst the pressure of the oil moving up the duct 42 (Figure 2)eventually lifts the-valve member 45 to allow oil to pass `to `actuallyeffect return movementof the table 1, whatever the pressure of the oilin the duct 42 it is unable to liit the valve member 39 owing to thefact that a small boreduct 51 (Figure 7) is provided leading 01T theduct 42 to the rear of the valve member `39 so that the pressure of theoil holds the valve member 39 against its seating.

As the table 1 returns the piston 5 enters the forward cylinder `3(Figure 1) expelling oil therefrom down the ducts 22, 2I (Figure 4) tothe pipe I1 which oil `movement is also assisted by the suction of theimpeller in the pipe I1.

It will thus be seen that for each cycle of the impeller a completefeeding cycle ris effected so `that the speed of feed is dependant onthe speed at which the impeller is driven, whilst the distance the stripI3 is fed perifeeding cycle is dependant on the extent of oil movementto and fro via the pipes I6 and I1 fand block I between the impeller andcylinders 3,44 so that by-varying.v

the extent of oil movement the extent of feeding Amovement of the'table1 can be varied and so adjusted to suit requirements.

For this purpose the impeller is so arranged and `constructed to enablea variable oil movement to `be obtained. Referring to Figures 10, 11 and12 the-impeller comprises two pairs of plungers 68, -66 and 6I, 6Ioperating in1bushes62 in the wall `63 of the impeller housing, `the-pairof plungers 160, 86 which operate together enter a chamber 64communicating with the pipe I6, whilst in a similar manner the pair ofplungers 6I, 6I enter a chamber65 communicating with the pipe I1, theends of the plungers remote from said lc :harnber are each provided`withnrollers 66 for `pivoted to :support members Aor ,blocks 69, 10.

These pivoted members 161, 68 each :carry l-;uni versally pivotedthereon shoes 1I bearing :against the face of a swash plateor face camA12 crotatably mounted inthe cover 1-3 of ythe impeller housing anddriven in any suitable manner 1in timed relationship with the machine.

The blocks 69, `1I) have a screw .threaded engagement with the threadedportions 14, ,15 ofthe vertical shaft 16 rotatably mounted in theimpeller housing and having secured to its lupper end the aforesaidcontrol knob 20. Thethreaded portions 14, 15 of this shaft are ofopposite :hand so that on rotation of the shaft the blocks69, 10 areeither moved apart or towards one another. Thus by manipulating the knob20 the shoes `1I are either moved towards the centre ofthe lface `cam 12to reduce the stroke of the plungers `68.

60 and 6I, 6I so'that the minimum of oil movement takes place along thepipes I6, I1 `or said shoes 1I may be adjusted towards the periphery ofthe cam 12 to obtain maximum stroke of the plungers and consequentmaximum movementof oil along the pipes I6, I1 to operate the table 1 formaximum feeding movement of the strip I3.

The ends of the plngers 60, 6 8, 6I, 64I within the chambers 64, 65respectively are bored at '1;1 (Figure 13) to receive compressionsprings 18for abutment therein, the outer `ends of thesprings 18abutting the wall 63 of the impeller housing in order to maintain therollers 66 at theother ends of pistons in contact with `the pivotedmembers 61, 68.

The housing of the pump containing (the swash plate 12 and associatedmechanism servesas f a reservoir for oil at atmospheric pressure forgthe purpose of replenishing the two lines of oilunder pressure betweenthe impeller and the cylinders 3, 4 in order to make good any loss. Forthis purpose communication is eiectel between the housing of the pumpand the chambers 6,4, 65 ,bv means of automatic valves contained in --atleast one plunger 60 or 6I of each pair.

The automatic valve of one of the plungers 60 is shown in Figure 13`from which it will be seen that the roller 66 is carried by a forkedhead 80 having a shank 8I itting in a bore 82 in theother end of theplunger 60, said shank having an axial through bore 83 therein.

Located in the bore 82 for limited sliding movement between the innerend of the shankBI and the annular shoulder 84 in the plunger 60 is 'avalve member 85 the full diameter `portion 860i which is an oil tightsliding iit in the 4bore 82 and when in the-position shown closes theinner end of the bore 83 in the shank 8l from the bore-11 and hence fromcommunication with the charnber 64, the valve member 85 being urged tothis position by pressure of oil thereon frornsaid chamber.

However, upon a fall in oil pressure in the chamber 64 and as thepistonri eiTects an outward suction stroke therein the suction on thevalve member 85 moves it towards Yand against the annular shoulder 84enabling oil to be inducted from the impeller housing through the bore83 in the shank 8| and via the reduced portion 81 of the valve member 85(which then registers with the annular groove 88 in the plunger) to thebore 11 and from thence into the chamber 64.

Inductance of oil through the above described automatic non-return valvein the'plungert-Evis promoted by virtue `ofthe `fact ftlfiatidue (to.the

7 action of the swash plate 'l2 the'plungers Bil, 50, 6l, 6I are notreciprocated at a constant speed. Thus after a quarter of the waythrough a feeding cycle when the swash plate has rotated through 90 theplungers 6i advancing into the chamber 65 to impel oil along the pipeIl' to the forward cylinder 3 advances a given distance but the plungers6U receding from the chamber El! to assist and accommodate returnmovement of oil from the pipe I6 have a slightly greater extent ofmovement creating a partial vacuum in the chamber 64 to assistinductance of oil through the plunger 60 that is fitted with theautomatic valve.

Halfway through the cycle the extent of move- Yment of the plungers 63,69 equals that of the vplungers 6I, and three quarters of the way'through the cycle a similar accelerated move- :ment of the plungers ti,6l receding from the Ichamber 65 takes place to create a partial Vacuumin the latter for promoting the desired cil inductance through anautomatic valve in one of the plungers 6l identical with that describedand shown in one of the plungers The arrangement of the annular grooveSe in relation to the reduced portion al of the valve member 85 is suchthat passage cf oil is only permitted when the valve member is fullyagainst lthe shoulder 84 otherwise too great a quantity of oil wouldtend to be inducted through the plunger.

claim:

l. Automatic feed mechanism for power presses and like machinescomprising in combination a base; a table mounted for reciprocatorymovement on said base; hydraulically operated grip- 'ping means adaptedto grip stock and mounted on said table for movement therewith; fixedhydraulically operated gripping means adapted to grip stock and mountedon said base so as to extend over the table in alignment with themovable gripping means on the latter; a pair of hydraulic rams mountedon said base and arranged to act in opposite directions on the table forimparting reciprocatory motion to the latter; a hydraulic impeller; ahydraulic system including two hydraulic fluid lines operativelyconnecting the impeller with the hydraulic rams. for reciprocation ofthe table; a further hydraulic system comprising a piston arranged foroperation by hydraulic fluid from at least one of the two :duid lines ofthe first mentioned hydraulic system Which piston is adapted to displacefluid to one of the gripping means and withdraw fluid from the other andvice versa -in order to alternately open and close the gripping means intimed relationship with the reciprocation of the table for effecting theautomatic intermittent feed of stock to a machine; and a further pistonarranged to be also operated on by uid from the two hydraulic fluidlines of the first mentioned hydraulic system and in conjunction withthe said piston of the hydraulic system for operating the grippingmeans, adapted to introduce 'lost-motion into the fluid movementalongthe two hydraulic fluid lines for the purposes of .causing thetable to pause at each extreme of its reciprocatory movement in order toenable the gripping action of the gripping means to be changed Whilstthe table is stationary.

2. Automatic feed mechanism for power press- -es and like machinescomp-rising in combination a base; a table mounted for reciprocatorymove- Iment on `said base; hydraulically operated griprping means.adapted to gripl stock and mounted on said table lfor movementtherewith; fixed hydraulically operated gripping means adapted to gripstock and mounted on said base so as to extend over the table inalignment with the Ymovable gripping means cn the latter; a pair ofhydraulic rams mounted on said base and arranged to act in oppositedirections on the table for imparting reciprocatory motion to thelatter; a variable stroke hydraulic impeller; a hydraulic systemincluding two hydraulic iluid lines operatively connecting the impellerwith the hydraulic Y rams for reciprocation of the table; a blockassembly in said base having fluidways therein for connecting said iluidlines to the rams; a further hydraulic system comprising a pistonslidable in a bore in said block assembly, said piston being arrangedfor operation by hydraulic iiuid from one of said fluid lines throughsaid fluidways in order to displace fluid from said bore to one of thegripping means and withdraw fluid from the other and vice versa so as toalternately open and close the gripping means in timed relationship withthe reciprocation of the table for effecting the automatic intermittentfeed of stock to a machine; and a further piston slidable in a bore insaid block assembly and arranged to be also operated on by fluid fromsaid fluid lines of the first mentioned hydraulic system through saidfluidways and in conjunction with the said piston of the hydraulicsystem for operating the gripping means adapted to introduce lost-motioninto the huid movement along the two hydraulic fluid lines for thepurposes of causing the table to pause at each extreme of itsreciprocatory movement in order to enable the gripping action of thegripping means to be changed whilst the table is stationary.

3. Automatic feed mechanism for power presses and like machinescomprising in combination a base; a table mounted for reciprocatorymovement on said base; hydraulically operated gripping means adapted togrip stock and mounted on said table for movement therewith; fixedhydraulically operated gripping means adapted to grip fixed stock andmounted on said base so as to extend over the table in alignment withthe movable gripping means on the latter; a pair of hydraulic ramsmounted on said base and arranged to act in opposite directions on thetable for imparting reciprocatory motion to the latter, cylinders ofsaid rams forming guides on which the table can slide for reciprocatorymovement; a variable stroke hydraulic impeller; a hydraulic systemincluding two hydraulic fluid lines operatively connecting the impellerwith the hydraulic rams for reciprocation of the table; a block assemblyin said base having uidways therein for connecting said uid lines to therams; a further hydraulic system comprising a piston slidable in a borein said block assembly, said piston being arranged for operation byhydraulic fluid from one of said fluid lines through said fluidways inorder to displace fluid from said bore to one of the gripping means andwithdraw fluid from the other and vice versa so as to alternately openand close the gripping means in timed relationship with thereciprocation of the table for effecting the automatic intermittent feedof stock to a machine; spring loaded valve means in said block assemblyfor controlling the direction and pressure of fluid movement in thefiuidways for conducting fluid from the said one of said fluid lines tosaid piston; and a further piston slidable in a bore in said blockassembly and arranged to be also operated on by fluid from said fluidlines of the first mentioned hydraulic system through said fluidways andin conjunction with the said piston of the hydraulic system foroperating the gripping means adapted to introduce lost-motion into thefluid movement along the two hydraulic uid lines for the purposes ofcausing the table to pause at each extreme of its reciprocatory movementin order to enable the gripping action of the gripping means to bechanged whilst the table is stationary.

4. A step by step feeding device for feeding sheet material with a stepby step motion, said device comprising a stationary material support, areciprocable material support, a primary pressure uid instrumentalityincluding a pressure uid pump for reciprocating said reciprocablesupport, and a pressure fluid actuated clamp mounted on each support,one of said clamps being reciprocable with said reciprocable support, incombination with a secondary self-contained sealed unit pressure iiuidinstrumentality including a free action type reciprocating piston, acylinder in which said piston reciprocates, conduit means connectingsaid clamps with said cylinder on opposite sides of said piston, and anaxial rod medially of which said piston is rigidly mounted, therespective ends of said rod being of reduced diameter with respect tothe corresponding operative face of said piston and being successivelysubjected to the pressure of the uid of said primary pressure liuidinstrumentality to alternately move said piston in opposite directionsto alternately supply uid under pressure to, and Withdraw fluid from,said clamps at the end of each step by step movement of saidreciprocable support and before the initiation of the succeeding step bystep movement thereof, whereby the reciprocable support will remain at astandstill while the fluid is being forced to one clamp and beingwithdrawn from the other clamp and until the space occupied by thedisplaced portion of the piston rod has been filled with oil when theinitiation of the next step by step movement will take place.

5. A step by step feeding device for feeding sheet material with a stepby step motion, said device comprising a stationary material support, areciprocable material support, a primary pressure fluid instrumentalityfor reciprocating said reciprocable support, and a pressure fluidactuated clamp mounted on each support, one of said clamps beingreciprocable with said reciprocable support, in combination with asecondary selfcontained sealed unit pressure uid instrumentalityincluding a reciprocating piston, a cylinder in which said pistonreciprocates, conduit means connecting said clamps with said cylinder onopposite sides of said piston, and an axial rod media-ily of which saidpiston is rigidly mounted, the respective ends of said rod being ofreduced diameter with relation to the corresponding operative faces ofsaid piston and being successively subjected to the pressure of thefluid of the primary pressure iluid instrumentality to alternately movesaid piston in opposite directions to alternately supply uid underpressure to, and withdraw fluid from, said clamps.

6. A step by .step feeding device for feeding sheet material with a stepby step motion, said device comprising a stationary material support, areciprocable material support, a primary pressure iluid instrumentalityfor reciprocating said reciprocable support, and a pressure fluidactuated clarnp mounted on each support, one of said clamps beingreciprocable with said reciprocable support, in combination with asecondary pressure fluid instrumentality including a double actingsecondary system pump and conduit means connecting said clamps With saidpump, said pump having portions successively subjected to the pressureof the fluid of said primary pressure duid instrumentality to operatesaid pump to alternately supply fluid under pressure to, and withdrawfluid from, said clamps at the end of each step by step movement of saidreciprocable support and before the initiation of the succeeding step bystep movement thereof, whereby the reciprocable support will remain at astandstill while the fluid is being forced to one clamp andsimultaneously is being withdrawn from the other clamp.

CHARLES EDWARD TALLIS.

References Cited in the iile of this patent UNITED STATES PATENTS NumberName Date 1,257,507 Malocsay Feb. 26, 1918 1,297,341 Gail Mar. 18, 19192,228,245 Barker et al Jan. 14, 1941 2,344,565 Scott et al Mar. 21, 19442,467,740 Haller Apr. 19, 1949

